Tritium concentrations in pine needle, litter and soil samples.

Samples of pine needle, litter and soil samples collected in/around Akita City and Rokkasho Village in 1989 were analyzed for both free water 3H (FWT) and organically-bound 3H (OBT). The FWT concentrations decrease in the order, litter or soil > pine needle. FWT concentrations in soil depend on the moisture content, and tend to increase with decreasing soil moisture content. This relationship is consistent with the observation that FWT in the soil increases with oxidation of atmospheric tritiated hydrogen gas (HT) and decreases with rainwater dilution. The OBT concentrations increase in the order pine needle < litter < soil at most of the sampling locations. This suggests that historically high soil 3H concentrations may be reflected as high OBT concentrations in soils of the present.